Abstract: In order to understand the genetic difference and phylogenic relationship within and among the Fusarium species in Section Martiella, the genetic diversity of 21 Fusarium strains in the section was examined by intersimple sequence repeats (ISSR). Fifteen selected ISSR primers were adopted to do amplification, and a total of 239 bands were amplified, among which, 230 (96.2%) were polymorphic, with an average of 15.3 polymorphic bands per primer. The genetic similarity ranged from 0.494 to 0.933, with an average of 0.640. All the test strains were clustered into two groups at genetic similarity of 0.593. The strains 1-17 were grouped into IG-I, belonging to Fusarium solani and F. solani var. coeruleum, while the strains 18-21 were grouped into IG-II, belonging to F. ventricosum. All the 21 strains could be entirely distinguished at genetic similarity of 0.933. The SSR loci in the Fusarium genomes were rich in polymorphism. The ISSR grouping had definite correlation with the species classification, but less correlation with the geographic origin of the strains. Within the same ISSR groups, there existed definite correlation between the genetic similarity and the geographic origin of the strains. Within the same species collected from the same regions and same host plants, there existed definite genetic difference among the strains of the same species.  

Key words: Fusarium strains in Section Martiella, molecular marker, ISSR-PCR, genetic diversity.